before vowels phen-, word-forming element in science meaning "pertaining to or derived from benzene;" see -phene.
word-forming element used in modern science to mean "of a cell," from Latinized form of Greek kytos "a hollow, receptacle, basket" (see cyto-).
word-forming element in science meaning "rain," from Greek hyetos "rain," from hyein "to rain," from PIE root *seue- (2) "take liquid" (see sup (v.2)).
word-forming element used in science to mean "twisted," from Latinized combining form of Greek streptos "twisted, easy to bend, pliant," verbal adjective of strephein "to turn, twist," from PIE root *streb(h)- "to wind, turn."
before vowels loph-, word-forming element used in science from 19c. and meaning "crest," from Greek lophos "neck of draught animals and men; crest of a helmet, crest of a hill, ridge," also "tuft on the head of birds, crest of feathers, cockscomb," a word of uncertain origin.
before vowels pter-, word-forming element in science meaning "feather; wing," from Greek pteron "wing," from PIE *pt-ero- (source also of Sanskrit patram "wing, feather," Old Church Slavonic pero "pen," Old Norse fjöðr, Old English feðer), from root *pet- "to rush; to fly."
word-forming element meaning "small in size or extent, microscopic; magnifying;" in science indicating a unit one millionth of the unit it is prefixed to; from Latinized form of mikros, Attic form of Greek smikros "small, little, petty, trivial, slight," perhaps from PIE *smika, from root *smik- "small" (source also of Old High German smahi "littleness"), but Beekes thinks it a Pre-Greek word.
word-forming element meaning "below, beneath," from Latin infra (adverb and preposition) "below, underneath, on the under side, beneath," also "later than; smaller than; inferior to," related to infernus "low, below," from PIE *ndher "under" (source also of Sanskrit adnah "below," Old English under "under, among;" see under). Modern popular use of it dates from the 1920s, as an opposite to super-, often in science fiction. "This use of infra- is scarcely a Latin one" [OED].
word-forming element, especially in scientific compounds, meaning "life, life and," or "biology, biology and," or "biological, of or pertaining to living organisms or their constituents," from Greek bios "one's life, course or way of living, lifetime" (as opposed to zoe "animal life, organic life"), from PIE root *gwei- "to live."
The correct usage is that in biography, but since c. 1800 in modern science it has been extended to mean "organic life," as zoo-, the better choice, is restricted in modern use to animal, as opposed to plant, life. Both are from the same PIE root. Compare biology.
word-forming element of Greek origin meaning 1. "after, behind; among, between," 2. "changed, altered," 3. "higher, beyond;" from Greek meta (prep.) "in the midst of; in common with; by means of; between; in pursuit or quest of; after, next after, behind," in compounds most often meaning "change" of place, condition, etc. This is from PIE *me- "in the middle" (source also of German mit, Gothic miþ, Old English mið "with, together with, among").
The notion of "changing places with" probably led to the senses of "change of place, order, or nature," which was a principal meaning of the Greek word when used as a prefix (but it also denoted "community, participation; in common with; pursuing").
The third, modern, sense, "higher than, transcending, overarching, dealing with the most fundamental matters of," is due to misinterpretation of metaphysics (q.v.) as "science of that which transcends the physical." This has led to a prodigious erroneous extension in modern usage, with meta- affixed to the names of other sciences and disciplines, especially in the academic jargon of literary criticism: Metalanguage (1936) "a language which supplies terms for the analysis of an 'object' language;" metalinguistics (by 1949); metahistory (1957), metacommunication, etc.